The present invention relates to a composition of matter and process for preparation of a propenamide based gel which is used as a cooling medium in a color variation inducing device capable of inducing color variation in toy articles bearing thermochromic materials.
Toys using thermochromic or light sensitive materials embedded or mixed in plastic printed on paper or plastic, or impregnated in fibers used for clothing, doll hair or the like are all very well known. In U.S. Pat. Nos. 4,917,643 and 5,503,583 there are disclosed dolls and toy vehicles containing surface coatings of thermochromic materials which change color upon a child""s application of warm or cold water. In still other applications going back in time, in U.S. Pat. No. 3,382,607 (May 14, 1968) a toy figure having synthetic hair fibers impregnated with an indictor dye which changes color in response to contact with liquids of varying pH levels. While a host of color changing toy devices and mechanisms (e.g. thermochromic) are known, very few means or devices have been proposed to actuate a color change in a thermochromic environment by contact with a heating or cooling source.
In Laid open Japanese Utility Model Application No 62-139573 there is disclosed the concept of bringing an electrical heating utensil, equipped with a heating resistor such as of tungsten or nickel, into contact with a thermally color varying material formed on the surface of an animal toy or the like, thereby inducing a color variation in the contacted are a. In U.S. Pat. No. 5,502,967 to Nakagawa et al. there is disclosed a variable hot/cold electrothermal device which can be positioned in contact with a thermally color varying surface area, thereby inducing color variation in the contacted zone. This patented device, while effective, is electrically sophisticated and, accordingly, is expensive and impractical for exploitation by young children in connection with a toy. Moreover, the device is outfitted with heating elements which will doubtlessly pose safety problems with any prospective use in the toy industry. For practical economic and safety purposes, any toy articles bearing thermochromic materials generally must rely on household water temperatures or ice cooling systems for actuation of the color variation in such articles.
The present invention is directed to a cooling gel composition and its use in a simple toy contact device. Color variations in household articles containing thermochromic materials by cooling means has generally required the use of cold water or ice pieces, or by keeping the thermally color varying article in a refrigerator. Such cooling means to induce color variation in thermochromic material may be applicable in certain specified places such as in the home, but are not generally usable elsewhere. Therefore, this cooling media, being limited in duration of a required low temperature (coldness), requires a cumbersome operation each time of use. Moreover, the thermally color varying articles are generally not water resistant and, consequently, are often deteriorated by water drops resulting from direct contact with the cooling medium (e.g. ice) or from leaking of a container housing the acqueous cooling medium.
In developing a cooling gel and color variation induction device herein, it has remained imperative that the gel materials be safe for young children. Safety requirement have evolved through the years as safety concerns have grown. Generally, safety requirement mandate that play material compositions be nonirritating to the skin or eyes or the like, and be nontoxic if ingested. Additional requirements have been expected of these materials to avoid damage to clothing, upholstery fabric, or carpeting.
Cooling gels are known for use in cooling media and are otherwise known as chilling gels, coldness-keeping gels, coldness -keeping heat transfer medium, colloidal coolant, coolant composition of ice pillow. However, these known coolant gels are generally not satisfactory for toy use because they are generally cryogens (freezing mixtures) having (i) high heat absorbancy, rendering them useful as refrigerant gels in portable containers, and (ii) are generally composed of chemicals, including freeze lowering additives, both of which characteristics are incompatible and/or unsafe for toy use.
The present invention is directed to a gel composition comprised of homopolymers and copolymers or crosslinked homopolymers and copolymers of 2-propenenitrile and 2-methyl-2-propenenitrile. Gel compositions are aqueous compositions generally thickened with gums, starches, resins, fine silica or other water absorbants. The instant polymeric materials are excellent water absorbents and it has been found that they form firm, strong gels having excellent cold retention and heat absorbency properties comparable or equal to ice (water) or ice cream but more enduring and steady in cold retention (melting rate) Accordingly, the instant gels are acceptable for toy use in that they have the required child safety features in terms of the gel materials and contact heat loss from a frozen or cold form of these gels. Additionally, these absorbent polymers can be cleaned up and removed from carpets and fabrics with water should they escape from a contemplated container.
The present invention is based on the discovery that homopolymers an copolymers or crosslinked homopolymers and copolymers of 2-propenenitrile and 2-methyl-2-propenenitrile have superior water absorbent properties to form firm gels having good thermodynamic properties in terems of high cold retention properties enabling the material to function as a cooling gel medium, particularly suited for toy use. These polymers additionally possess a non-toxic character and are water miscible thereby rendering them usable as, or in, toy devices. The invention comprises a novel gel composition, its use in a color variation inducing device, and processes for making and using the gel composition. The gel composition is comprised of water, homo-polymers and copolymers of 2-propenenitrile and 2-methyl-2-propenenitrile and a significant amount of a preservative comprising alkyl parabens. The gel can be used as a cooling medium which is firm, strong, highly flexible and elastic, and provides a comfortable touch. The gel peels and fragments so that it may be packed in a container for coolant gel use. Further the gel may be molded to have a desired shape and dimensions and immediately used as a final product without the need of a shaping operation.
In accordance with the present invention, there is provided a strong, elastic, non-toxic cooling gel composition which has a firm gelatin character, a comfortable touch and moistened feeling. The gel is comprised of (i) at least 90% by weight of water, (ii) an absorbent comprised of saponified polymers or copolymers of 2-propene-nitrile and 2-methyl-2-propenenitrile in a lesser amount than water, and (iii) still lesser amounts of a preservative selected from the group of alkyl parabens consisting essentially of methyl, ethyl, propyl, and butyl parabens (p-hydroxy benzoate) and mixtures thereof. A preferred absorbent used herein is the corlymer poly(2-propenamide-co-2-propenoic acid, the sodium salt). The present gels are child user friendly and cold retentive because they can be cooled at temperatures of from about below freezing temperatures (freezer cooling) up to 45xc2x0 F. (refrigerator cooling) and retain such lower temperatures over hours of time. It is this feature in combination with low temperature thermochromic dyes which can be exploited by children to induce color variation n countless toy items.
The instant cooling gel composition is employed in a color variation inducing device which in combination with a color-varying system enables applications to various fields including toys. The instant device provides a casing or housing for encasing and supporting the instant cooling gel, said casing being in the form of an elongated cylindrical applicator having a lateral wall defining a circumferential shaft for gripping, around the device. The device is rendered functional by cooling the gel filled application to temperatures of at least as low as 32xc2x0 F. to 40xc2x0 F. and applying it to a low temperature thermochromatic or color varying containing surface. The cooling) gel-filled applicator can be employed with toys containing thermochromic dyes or pigments to produce a variety of patterns, designs, numbers, letters, or other indicia which change color as the temperature of the thermochromic containing surfaces of the toys varies.
In one preferred form, a cooling gel composition is comprised of (i) at least 90% by weight of an aqueous portion; (ii) at least 3 weight percent of an absorbent comprised of saponified polymers or copolymers of 2-propenenitrile and 2-methyl-2-propenenitrile; and (iii) at least 1% by weight of an alkyl paraben preservative selected for the group of consisting essentially of methyl, ethyl, benzyl, and propyl parabens (p-hydroxy benzoate) and mixtures thereof. The composition further may optionally includes appropriate small amounts of humectants, plasticizers, fragrances or gel colorants depending on the toy application of the gel contemplated.
The present toy play gel composition is prepared by:
a) mixing water and an alkyl paraben preservative selected for the group of consisting essentially of aryl-alkanols, methyl, ethyl, propyl, and butyl parabens (p-hydroxy benzoate) and mixtures thereof to form an aqueous solution and water at an elevated temperature, to form a solution; and
b) concurrently adding and mixing an absorbent comprised of polymers or copolymers of 2-propenenitrile and 2-methyl-2-propenenitrile until a strong, firm gelatin is formed.